JP2009214758A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep the earth removing performance of a lag groove provided on a tread portion. <P>SOLUTION: The pneumatic tire 1 has the lag groove 4 extending so as to intersect a tire circumferential direction, at least on a tread surface 2a of a tread portion 2. The pneumatic tire 1 is provided with a protrusion 6 projecting toward an opening 4b of the lag groove 4 from a groove bottom 4a of the lag groove 4. At least two protrusions 6 are provided so as to gradually decrease the dimensions of a rubber cross section in a groove width direction (a groove wall 4a direction) of the lag groove 4 from the groove bottom 4a toward the opening 4b of the groove 4, tilt in the groove width direction of the lag groove 4, and make the tilting alternate with each other in an extending direction of the lag groove 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that is applied when traveling in a muddy ground and has a soil removal performance in a lug groove provided in a tread portion.

  In a pneumatic tire having a block provided with a circumferential groove extending in the tire circumferential direction and a lug groove extending across the tire circumferential direction in the tread portion, in order to travel in a muddy ground, the lug It is necessary to grip the mud efficiently by the groove and kick it out. Moreover, after the mud is kicked out by the lug groove, the mud is kicked out next by the lug groove as the tire rotates, so it has a soil discharging performance to discharge from the lug groove so that the gripped mud is not clogged. It is considered important.

  Conventionally, in this type of pneumatic tire, pleated protrusions extending in the groove direction and projecting from the wall surface in an inclined direction toward the tire surface are provided on both wall surfaces of the lug groove. The pleated projections provide a soil removal performance for discharging the clogged mud in the movement from the stage where the clogged clay clogs the lug groove to the kicking out (for example, Patent Document 1). reference).

JP 2004-58936 A

  However, since the conventional pneumatic tire described above has many opportunities to travel off-road including muddy ground, the pleated projections provided on the wall surface are easily damaged by stone biting in the lug groove, etc. The soil removal performance is degraded due to the damage of the protrusions.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can always maintain a soil removal performance.

  In order to achieve the above object, in the pneumatic tire according to the present invention, in the pneumatic tire having a lug groove extending at least on the tread surface of the tread portion so as to intersect the tire circumferential direction, the pneumatic tire has a groove from the groove bottom of the lug groove. A protrusion protruding toward the opening of the lug groove is provided, and the protrusion is formed such that the size of the rubber cross section in the groove width direction of the lug groove gradually decreases from the groove bottom of the lug groove toward the opening, And while being inclined in the groove width direction of the lug groove, at least two are provided in such a manner that the inclination is staggered in the extending direction of the lug groove.

  According to this pneumatic tire, the protrusions are provided so as to protrude from the groove bottom of the lug groove toward the opening of the lug groove, and are formed gradually smaller from the groove bottom of the lug groove toward the opening, And by being inclined and provided in the groove width direction of the lug groove, it has a predetermined strength and has an elastic force toward the opening side of the lug groove. In addition, the protrusions are alternately provided in the extending direction of the lug grooves, so that the inclination of the protrusions is increased with the opening and closing of the lug grooves when the tire rotates and the block contacts and leaves the road surface. Different mutual spacing changes.

  For this reason, when traveling in a muddy area, mud, stones, etc. gripped by the lug grooves are discharged as they are handled by mutual protrusions with different inclinations due to their strength and elasticity as the tire rotates. The For this reason, it has good soil removal performance, can also prevent stone biting and the like, and can reduce breakage of protrusions due to stone biting and the like. As a result, the soil removal performance can always be maintained.

  In the pneumatic tire according to the present invention, the height h of the protrusion protruding from the groove bottom of the lug groove is 0.30 ≦ h / GD ≦ 0. It is characterized by being set in the range of 50.

  According to this pneumatic tire, when the height h of the protrusion is less than 30 [%] of the groove depth GD of the lug groove, an effective soil removal effect cannot be obtained. On the other hand, when the height h of the projection exceeds 50 [%] of the groove depth GD of the lug groove, the volume of the lug groove decreases and an effective driving force when traveling in a muddy area cannot be obtained. Protrusion breakage is likely to occur due to stone chewing. That is, by setting in the range of 0.30 ≦ h / GD ≦ 0.50, an effective soil removal effect can be obtained, and breakage of the protrusion due to stone biting or the like can be prevented.

  In the pneumatic tire according to the present invention, the protrusion has a triangular cross section in the groove width direction of the lug groove, and is inclined to the tangent line of the tread portion at the center of the lug groove. The side angle α is set in a range of 40 [degrees] ≦ α ≦ 70 [degrees].

  According to this pneumatic tire, when the angle α is less than 40 [degrees] or more than 70 [degrees], an effective soil removal effect cannot be obtained. In other words, an effective soil removal effect can be obtained by setting in a range of 40 [degrees] ≦ α ≦ 70 [degrees].

  Moreover, in the pneumatic tire according to the present invention, the protrusion is separated from the intersection of the groove bottom and the groove wall of the lug groove by a distance W from the opposite side of the inclination to a portion protruding from the groove bottom of the lug groove. And the distance W is set in a range of 0.20 ≦ W / Wr with respect to the groove width Wr of the lug groove.

  According to this pneumatic tire, when the distance W is less than 20 [%] of the groove width Wr of the lug groove, an effective space cannot be secured between the protrusion and the groove wall of the lug groove, and the soil removal effect is obtained. It will drop and induce mud clogging. That is, by setting the range to 0.20 ≦ W / Wr, an effective soil removal effect can be obtained.

  Further, in the pneumatic tire according to the present invention, the protrusion has a total length L of a tip portion in the extending direction of the lug groove, and a length Lr in the extending direction of the lug groove provided with the protrusion. On the other hand, it is set in the range of 0.30 ≦ L / Lr.

  According to this pneumatic tire, when the total length L of the protrusions is less than 30 [%] of the lug groove length Lr, an effective soil removal effect cannot be obtained. That is, an effective earth removal effect can be obtained by setting the range of 0.30 ≦ L / Lr.

  The pneumatic tire according to the present invention can always maintain the soil removal performance of the lug groove provided in the tread portion.

  Embodiments of a pneumatic tire according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  In the following description, the tire radial direction means a direction orthogonal to the rotational axis of the pneumatic tire, and the tire radial direction outer side means a side away from the rotational axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. The tire width direction means a direction parallel to the rotation axis, and the tire width direction outer side means a side away from the tire equatorial plane in the tire width direction.

  1 is a plan view showing a part of a tread portion of a pneumatic tire according to an embodiment of the present invention, FIG. 2 is a sectional view showing a lug groove, and FIG. 3 is another embodiment of a lug groove protrusion. FIG. 4 is a schematic plan view showing a lug groove, and FIG. 5 is a chart showing the results of a performance test of a pneumatic tire according to an embodiment of the present invention.

  The pneumatic tire 1 is formed with a tread portion 2 that is formed of an elastic rubber member and forms an outline of the pneumatic tire 1 on the outermost side in the tire radial direction. In addition, a plurality of circumferential grooves 3 extending in the tire circumferential direction are formed on the tread portion 2, that is, on the tread surface 2 a that comes into contact with the road surface when a vehicle (not shown) equipped with the pneumatic tire 1 travels. A plurality of blocks 5 are formed by the plurality of lug grooves 4 extending so as to intersect the tire circumferential direction. A narrow groove-shaped sipe 5a is formed on the surface (tread surface) of the block 5.

  In the pneumatic tire 1, a protrusion 6 is provided on the groove bottom of the lug groove 4. The protrusion 6 is provided so as to protrude from the groove bottom 4 a of the lug groove 4 toward the opening 4 b of the lug groove 4. The protrusion 6 is formed such that the size (thickness) of the rubber cross section in the groove width direction (direction of the groove wall 4c) of the lug groove 4 is gradually reduced from the groove bottom 4a of the lug groove 4 toward the opening 4b. . Furthermore, a plurality of (at least two) protrusions 6 are provided in a manner in which the protrusions 6 are inclined in the groove width direction of the lug grooves 4, and the inclinations are staggered (staggered) in the extending direction of the lug grooves 4 (FIG. 2). reference).

  The protrusion 6 having such a structure is provided so as to protrude from the groove bottom 4a of the lug groove 4 toward the opening 4b of the lug groove 4, and is formed to be gradually smaller from the groove bottom 4a of the lug groove 4 toward the opening 4b. And being provided in a slanted direction in the groove width direction of the lug groove 4 has a predetermined strength and an elastic force toward the opening 4b of the lug groove 4. Moreover, the protrusions 6 are alternately provided in the direction in which the lug grooves 4 extend, so that the lugs 4 can be opened and closed when the tire rotates and the block 5 contacts and separates from the road surface. Along with this, the mutual intervals with different inclinations change.

  For this reason, when traveling on a muddy ground, the mud, stones, etc. gripped by the lug grooves 4 are handled by the mutual protrusions 6 having different inclinations due to the strength and elasticity of the tire as the tire rotates. Discharged. As described above, the pneumatic tire 1 according to the present embodiment has good soil removal performance, can also prevent stone biting and the like, and can reduce damage to the protrusions 6 due to stone biting and the like. As a result, it is possible to always maintain the soil removal performance.

  In the pneumatic tire 1 according to the present embodiment, the protrusion 6 has a height h protruding from the groove bottom 4 a of the lug groove 4 with respect to the groove depth GD of the lug groove 4. It is preferably set in the range of GD ≦ 0.50, that is, in the range of 30 [%] ≦ h / GD ≦ 50 [%].

  When the height h of the protrusion 6 is less than 30 [%] of the groove depth GD of the lug groove 4, an effective soil removal effect cannot be obtained. On the other hand, when the height h of the protrusion 6 exceeds 50 [%] of the groove depth GD of the lug groove 4, the volume of the lug groove 4 decreases and an effective driving force when traveling in a muddy area is obtained. In addition, the protrusions 6 are liable to be damaged due to a stone bite or the like. The groove depth GD of the lug groove 4 is from the deepest position of the groove bottom 4 a of the lug groove 4 to the surface (opening 4 b) of the tread part 2, and the tread part 2 at the center of the groove width of the lug groove 4. A distance parallel to the normal R.

  Further, in the pneumatic tire 1 according to the present embodiment, the protrusion 6 has a triangular rubber cross-sectional shape in the groove width direction of the lug groove 4, and the tread portion 2 in the center of the groove width of the lug groove 4. It is preferable that the angle α of the inclined side with respect to the tangent line is set in a range of 40 [degrees] ≦ α ≦ 70 [degrees].

  When the angle α is less than 40 [degrees] or exceeds 70 [degrees], an effective soil removal effect cannot be obtained. Moreover, it is preferable that the protrusion 6 has a triangular long side provided toward the opening 4b of the lug groove 4 in order to obtain an effective soil removal effect. In FIG. 2, the tangent line of the tread portion 2 at the center of the groove width of the lug groove 4 is shown as a reference line S parallel to the tangent line. As shown in FIG. 3, when the side of the protrusion 6 is formed as an arc, the angle α is equal to the tangent A at the position of 50% (half) of the height h of the protrusion 6 and the lug groove. 4 is defined by the angle formed by the tangent (reference line S) of the tread portion 2 at the center of the groove width.

  Further, in the pneumatic tire 1 according to this embodiment, the protrusion 6 protrudes from the groove bottom 4a of the lug groove 4 on the opposite side of the inclination from the intersection B of the groove bottom 4a of the lug groove 4 and the groove wall 4c. The distance W is provided to the part, and the distance W is set to a range of 0.20 ≦ W / Wr with respect to the groove width Wr of the lug groove 4, that is, a range of 20 [%] ≦ W / Wr. It is preferable. Further, it is more preferable that the range is set to 0.20 ≦ W / Wr ≦ 0.40.

  When the distance W is less than 20 [%] of the groove width Wr of the lug groove 4, an effective space cannot be secured between the protrusion 6 and the groove wall 4c of the lug groove 4, and the soil removal effect is reduced, resulting in mud. It will cause clogging. The groove width Wr is defined by a width reference line T parallel to the tangent line of the tread portion 2 at the center of the groove width of the lug groove 4 and the groove wall 4c at a position of 50% (half) of the groove depth GD. Is the shortest distance between the intersection points C. Usually, the groove width Wr is set in a range of 10 [mm] ≦ Wr ≦ 30 [mm]. In addition, when the groove bottom 4a and the groove wall 4c of the lug groove 4 are connected by an arc, the intersection of the extended lines of the groove bottom 4a and the groove wall 4c is defined as an intersection B. When the groove bottom 4a of the lug groove 4 and the portion protruding from the groove bottom 4a of the protrusion 6 are connected by an arc, the intersection of the groove bottom 4a and the extension line of the protrusion 6 is defined as the groove bottom of the protrusion 6 It shall be the part which protrudes from 4a.

  Further, in the pneumatic tire 1 according to the present embodiment, as shown in FIG. 4, the protrusion 6 is provided with the total length L (L1 + L2 + L3 + L4) of the tip end portion in the extending direction of the lug groove 4. The length Lr in the extending direction of the lug groove 4 is preferably set in a range of 0.30 ≦ L / Lr, that is, in a range of 30 [%] ≦ L / Lr.

  When the total length L of the protrusions 6 is less than 30 [%] of the length Lr of the lug grooves 4, an effective soil removal effect cannot be obtained. Note that the lug groove 4 shown in FIG. 1 is not formed linearly in the extending direction. In this case, the length Lr in the extending direction is the shortest length in the extending direction. In addition, as long as the protrusions 6 are alternately arranged, the lengths of the protrusions 6 do not have to be uniform, and the lengths of the protrusions 6 may be appropriately changed depending on the groove width, groove shape, and the like of the lug grooves 4. Moreover, in order to ensure sufficient soil removal performance, it is preferable to provide two or more pairs of protrusions 6 having different slopes.

  In the above-described embodiment, the protrusions 6 having different inclinations do not have to be symmetrical, and may be appropriately changed according to the groove width and groove depth of the lug groove 4. In addition, as shown in FIG. 4, the protrusions 6 having different inclinations may be provided intermittently in the extending direction of the lug groove 4, but are provided continuously and integrally in the extending direction of the lug groove 4. It may be done. Moreover, although the form provided in the lug groove 4 which makes the block 6 of the tire width direction outermost (shoulder region) block 5 is shown in FIG. 1, the protrusion 6 may be provided in the other lug groove 4.

  In the present embodiment, performance tests regarding the clogging of the lug grooves 4 and the damage resistance of the protrusions 6 were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 5).

  In this performance test, a pneumatic tire having a tire size of 285 / 65R17 is used. The pneumatic tire was assembled on a 17 × 8JJ rim, mounted on a four-wheel drive vehicle, and an air pressure of 230 [kPa] was applied at the front and rear. In the evaluation method, in the clogging state of the lag grooves (muddy ground traveling performance), the clogging of the lag grooves when traveling at a speed of 50 [km / h] for 200 [m] was investigated. Then, based on the result of this investigation, an index evaluation is performed with the conventional example as a reference (100). This evaluation is more preferable as the numerical value is larger. Further, the damage resistance of the protrusions was evaluated by measuring the damage state (the number of damages) of the protrusions when traveling on a rough road such as a rocky road at a speed of 50 [km / h] for 1 [km]. This evaluation is more preferable as the numerical value (number of damages) is smaller.

  The conventional pneumatic tire has a protrusion on the groove wall of the lug groove, and the protrusion length of the protrusion is 2 [mm] to 5 [mm]. The pneumatic tires of Examples 1 to 7 have protrusions on the groove bottom of the lug groove, the height h [%] of the protrusion, the angle α [degree] of the protrusion, and the distance W [%] at the groove bottom. ] And the total length L [%] of the protrusions are made appropriate.

  As shown in the test results of FIG. 5, it can be seen that in the pneumatic tires of Examples 1 to 7, the clogged state of the lug grooves and the damage resistance of the protrusions are improved.

  As described above, the pneumatic tire according to the present invention is applied when traveling on a muddy ground or the like, and is suitable for maintaining the soil removal performance of the lug groove provided in the tread portion.

It is a top view which shows a part of tread part of the pneumatic tire concerning embodiment of this invention. It is sectional drawing which shows a lug groove. It is sectional drawing which shows other embodiment of the processus | protrusion of a lug groove. It is a schematic plan view which shows a lug groove. It is a graph which shows the result of the performance test of the pneumatic tire concerning embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 2a Tread surface 3 Circumferential groove 4 Lug groove 4a Groove bottom 4b Opening 4c Groove wall 5 Block 5a Sipe 6 Protrusion h Protrusion height α Protrusion angle B Intersection of groove bottom and groove wall W Protrusion Distance from intersection B of Wr Groove width L Total length of protrusion Lr Extended length of lug groove R Normal of tread part at center of groove width of lug groove S To tangent of tread part at center of groove width of lug groove Parallel reference line

Claims (5)

In a pneumatic tire having at least a lug groove that extends across the tire circumferential direction on the tread surface,
Protrusions projecting from the groove bottom of the lug groove toward the opening of the lug groove are provided,
The protrusion is formed such that the size of the rubber cross section in the groove width direction of the lug groove is gradually reduced from the groove bottom of the lug groove toward the opening, and the inclination is inclined in the groove width direction of the lug groove. A pneumatic tire characterized in that at least two tires are provided so as to be staggered in the extending direction of the lug grooves.   A height h protruding from the groove bottom of the lug groove is set in a range of 0.30 ≦ h / GD ≦ 0.50 with respect to the groove depth GD of the lug groove. The pneumatic tire according to claim 1.   The protrusion has a triangular cross section in the groove width direction of the lug groove, and the angle α of the inclined side with respect to the tangent of the tread portion at the center of the lug groove is 40 [degrees]. The pneumatic tire according to claim 1, wherein the pneumatic tire is set in a range of ≦ α ≦ 70 [degrees].   The protrusion is provided at a distance W from the intersection of the groove bottom and the groove wall of the lug groove to a portion protruding from the groove bottom of the lug groove on the opposite side to the inclination, and the distance W is The pneumatic tire according to claim 1, wherein the pneumatic tire is set to a range of 0.20 ≦ W / Wr with respect to the groove width Wr.   The protrusion has a total length L of the tip in the extending direction of the lug groove in a range of 0.30 ≦ L / Lr with respect to a length Lr in the extending direction of the lug groove provided with the protrusion. The pneumatic tire according to any one of claims 1 to 4, wherein the pneumatic tire is set to.

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